This invention relates to an electronic flipflop circuit which includes a data input, a data output and a clock signal input, including a first transmission gate for transferring binary data on the data input to an input of a first storage element under the control of the clock signal, a second transmission gate for transferring, under the control of the clock signal, the binary data at an output of the first storage element to an input of a second storage element which includes an output which constitutes the data output, each transmission gate including only one insulated gate field effect transistor having a channel for the transfer of the binary data, both gate electrodes receiving the same clock signal and the transistor in the first transmission gate being of a first conductivity type, and the transistor in the second transmission gate being of a second conductivity type.
A circuit of this kind is known from U.S. Pat. No. 4,390,987 which describes a flipflop circuit in which a storage element is provided at its input with a transmission gate which consists of a single transistor, the storage element itself also including a single transmission gate. Each of the two transmission gates consists of only one insulated gate field effect transistor, the transistor in one gate being a P-type, while the transistor in the other gate is an N-type. These two gates alternately produce an input signal at the input of a forward inverter.
A transmission gate which includes a P-channel transistor distorts a "low" signal so that the voltage at the input of the forward inverter cannot become lower than the threshold voltage of the P-channel transistor, whereas the associated transmission gate (consisting of an N-channel transistor) distorts a "high" signal so that the voltage at the input of its forward inverter cannot become higher than the supply voltage minus the threshold voltage of this transistor.
These distortions render the flipflop circuit very susceptible to electrical interference signals in, for example, the power supply leads, notably in the case of low supply voltages (for example, 3 volts), as well as to tolerances in the manufacturing process and changes in the ambient conditions.